Prostate cancer is a major cause of death among men in Western countries. The current protocol for detection of this cancer involves testing for prostate-specific antigen (PSA) levels. If PSA levels are found to be high (4 ng/ml), a tissue biopsy is performed. Unfortunately, PSA testing is limited by the fact that it lacks sensitivity and it does not distinguish between prostate cancer and benign prostate hyperplasia. As a result, many men either are not identified as having the disease or because of false positive tests are subjected to the invasive tissue biopsies when they do not have the disease. A much more specific and less invasive diagnostic test is needed for early detection of this disease.
Delta-catenin presents itself as an improved alternative to the PSA/biopsy tests currently utilized for prostate cancer detection. Delta catenin was first identified and patented (U.S. Pat. No. 6,258,929) as a neurospecific protein, alternatively named ALARM. At the time, the protein was believed to be expressed almost exclusively in brain tissue. However, Burger, et al. (Int. J. Cancer 100, 228-237 (2002)) subsequently found the messenger RNA for delta-catenin to be expressed in prostate cancer tumors with the delta-catenin transcripts being localized to the glandular secretory cells. Unlike PSA, delta-catenin was capable of distinguishing between prostate cancer and benign prostate hyperplasia. Burger et al. noted a possible diagnostic role for delta-catenin in prostate cancer detection. However, they also pointed out that a significant difficulty remained in development of this tool since delta-catenin had only been detected in glandular secretory epithelial cells in prostate tissues and had not been found in prostate stroma or bodily fluids, such as serum or urine.